Zigzag sewing machine

ABSTRACT

A zigzag sewing machine equipped with a timing mechanism for the needle bar and hook to equalize the related positions both when the latter is to take the loop at any oscillated position of the needle, said timing mechanism comprising a crank rod connected to the rotatable gear and to the needle bar for imparting the vertical reciprocation to the needle bar in accordance with the lateral oscillation thereof.

o Muted States Fateut [1s] 3,673,97 1 Ono July 4, 1972 [54] ZIGZAGSEWING MACHINE [56] References Cited [72] Inventor: Takeshi Ono, Kariya,Japan UNITED STATES PATENTS [73] Assignee: Aisin Seiki Kabushiki Kaisha,Kariya, 3,479,977 1 H1969 Meier. ..1 12/ 158 R Ja 1 3,247,817 4/1966Eguchl ..1 12/158 R 3,507,236 4/1970 Komuro ..1 12/158 R [22] Filed:Sept. 1, 1970 21 L 8 604 Primary Examiner-Patrick D. LawsonAttorneyPierce, Scheffler & Parker [30] Foreign Application PriorityD8118 57 ABSTRACT Sept. 4, 1969 Japan ..44/70l39 A zigzag Sewing machineequipped with a timing mechanism for the needle bar and hook to equalizethe related positions both when the latter is to take the loop at anyoscillated posi- 52 U.S. Cl. tion of the needle Said timing mechanismcomprising a crank IL CL rod connected to the rotatable gear and to theneedle bar for [58] Field of a B 158 C imparting the verticalreciprocation to the needle bar in ac- 1 i 58 cordance with the lateraloscillation thereof.

1 Claim, 5 Drawing Figures PKTENTEDJUL 4 I972 SHEET 2 0F 2 FIG. 3

/ ,IIIIII'IIIIIIIIII ZIGZAG SEWING MACHINE This invention relates tozigzag sewing machines, and more particularly to a novel and improvedtiming mechanism of a needle and a hook for the zigzag sewing machine.

The zigzag sewing machine has a shuttle mechanism including a hook totake a thread loop supplied from the needle. The hook is rotated orreciprocated in a fixed plane in spite of lateral oscillation of theneedle. This is undesirable because the relative position of the needleand hook is changed in dependence upon the needle position. Morespecifically, it is common use for the hook to take the loop when theneedle is positioned in the left position relative to the operator andraised up slightly from its lower dead center. Accordingly, the hook iscompelled to be late to take the loop when the needle is positioned tothe right, since the hook is required to rotationally advance from thecorresponding left position to the corresponding right position.

Consequently, it is liable to produce objectable skip-stitch andthread-cut.

Therefore, the principal object of the present invention is to providean improved zigzag sewing machine in which the height of the needle iscontrolled in dependence upon its laterally oscillated position wherebythe relative position of the needle and hook is substantially the sameat any oscillated position of the needle when the hook is to take theloop, so that the satisfactory zigzag sewing stitch can be obtained.

For an understanding of the principles of the invention, reference ismade to the following description of a typical embodiment thereof asillustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a front view partly in section of the zigzag sewing machineaccording to this invention, part of said machine being omitted;

FIG. 2 is a top plane view machine of FIG. 1;

FIG. 3 is a side elevation machine of FIG. 1;

FIG. 4 is a similar view.of FIG. 2,the constituent elements beingrepresented in a schematic way; and

FIG. 5 is a schematic view for explaining the operation of the timingmechanism of the sewing machine,

With reference to FIGS. 1 to 3, there is illustrated a zigzag sewingmachine having an arm head including a bracket arm 11. A horizontal mainshaft 12 is longitudinally journaled in a bearing 13 in the bracket arm11. A first bevel gear 14 is fixed to the end portion of the main shaft12 by means of a setscrew 15 thereby being driven in unison with themain shaft 12. A support shaft 16 is securely mounted by a setscrew 17on a protrusion 18 formed integrally with the bracket arm 11 and extendsat right angles to the axis of the main shaft 12. There is provided asecond bevel gear 19 which is rotatably mounted on the support shaft 16and is provided with the same numbers of teeth thereon as the firstbevel gear 14 to normally cooperate therewith.

The second bevel gear 19 comprises an integral pin' 20 which projectsfrom its top face eccentrically from the rotating center 0 (FIG. 5) ofthe second bevel gear 19. One end of a crank rod 21 is pivoted on theintegral pin 20 by a pin 22 while the other end thereof is pivoted on aneedle bar holder 23 fixed to a needle bar 24 adapted to support aneedle 25. Lateral vibration is imparted to the needle bar 24 by arocking member 32 pivotally mounted on one end of a rocking rod 34. Theother end of the rocking rod 34 is operatively connected to a zigzagwidth control box (not shown). The detailed operation of lateraloscillation of the needle 25 will be explained hereinafter withreference to FIG. 4, although the arrangement and operation form no partof the present invention.

A vertical shaft 26 is secured at each end to an upper boss 27 and alower boss 28 and is arranged to be positioned in the horizontal linepassing through the center C (FIG. 4) of the needle bar 24 as is seen inFIG. 2.

A shaftsupporting member 29 is pivotally mounted on the shaft 26 and hastwo lugs 30 and 31 at the ends thereof. The rocking member 32 isdisposed between the two lugs 30 and partly in section of the sewingpartly in section of the sewing 31 of the supporting member 29 and isoperatively connected thereto by a pin 37. The pin 37 is fixed to thetwo lugs 30 and 31 at each end while pivotally mounting the rockingmember 32 thereon. The rocking member 32 is provided with three lugs34', 35 and 36 as shown the upper lug 34' and one of the lower lugs 35being adapted to support the needle bar 24, and the other lower lug 36having a slide block 38 pivoted thereto by a setscrew 41.

The slide block 38 is reciprocable in the perpendicular direction inFIG. 2 within a slot 39 of a hub portion 40 formed integrally with thebracket 1 l. The axial center of the slot 39 is arranged to bepositioned in the same perpendicular line passing through the center A(FIG. 4) of the shaft 26 as is seen in FIG. 2. It should be noted thatthe needle bar 24 is prevented from rotating by the two lugs 34' and 35.

As is shown in FIG. 4, the oscillating mechanism including the shaft 26(A), and pin 37 (B), the needle bar 24 (C), and the setscrew 41 (D) isarranged as follows:

where, A is the center of axis of the shaft 26, B is that of the pin 37,C is that of the needle bar 24, and D is that of the setscrew 41.

When the needle bar 24 is urged to move by the rocking rod 34, theoscillating mechanism operates in a manner of socalled Scottruosellmovement, more particularly, the slide block 38 slides within the slot39 in the vertical direction in FIG. 4 by the angular displacement ofthe support member 29. Consequently, the needle bar 24 is oscillated inthe horizontal direction as indicated by the double-headed arrow so asto accomplish the zigzag stitch.

Referring to FIG. 5, 0 indicates the center of the second bevel gear 19,L and R indicate the left and right needle positions, respectively. Eand F indicate each end of the crank rod 21 at the left needle positionwhile E1 and F1 indicate the same at the right needle position. Locus ofone end E or E1 may be represented by a circle. 0L and OR are therotated ang'les of the second bevel gear 19 to position the needle 25 inthe left position and in the right position, respectively. The angle ORis larger than the angle 6L by the angle 5 that is to say, the angulardisplacement of the second bevel gear 19 by 4: is required to shift theneedle 25 to the right position from the left position. It should benoted that the angle 4) is nearly equal to the angle (#1 in which a hookin the shuttle mechanism is rotated from its left loop-taking positionto its right loop-taking position, because the rotated angle of thesecond bevel gear 19 is equal to that of the first bevel gear 14 drivenby the main shaft 12 and the main shaft 12 is operatively connected tothe shuttle mechanism to cooperate therewith as will be apparent tothose skilled in the art.

H indicates the height between the center 0 of the second bevel gear 19and the other end F of the crank rod 21 in which the needle bar 24 isslightly raised up from the lower dead center so as to permit the hook42 to take a thread loop (not shown).

The length and attachment of the crank rod 21 is arranged so that theheight between the center 0 and the other end F1 is equal to the heightII when the second bevel gear 19 is rotated by the angle 4:, and thehook 42 is rotated by the angle (1)].

Consequently, the relative positions of the needle bar 24 and the hook42 are the same both in the left needle position L and in the rightneedle position R when the hook 42 takes the loop supplied from theneedle 25, so that the satisfactory zigzag sewing stitch will beobtained.

What we claimed is 1. A zigzag sewing machine comprising a main shaft, afirst bevel gear mounted thereon, a second bevel gear engaging saidfirst bevel gear for rotation in a plane perpendicular to said firstbevel gear, a needle bar, a needle supported by said needle bar, a crankrod connecting said needle bar to said second bevel gear for reciprocalmotion in a vertical direction, means for laterally oscillating saidneedle bar, said means including an oscillating rod, and a rotating hookto take a thread 3 ,673 ,971 3 4 loop supplied by said needle, saidsecond bevel gear being rotated in a direction opposite to the hookwhereby the hook takes the thread loop supplied by said needle.

1. A zigzag sewing machine comprising a main shaft, a first bevel gearmounted thereon, a second bevel gear engaging said first bevel gear forrotation in a plane perpendicular to said first bevel gear, a needlebar, a needle supported by said needle bar, a crank rod connecting saidneedle bar to said second bevel gear for reciprocal motion in a verticaldirection, means for laterally oscillating said needle bar, said meansincluding an oscillating rod, and a rotating hook to take a thread loopsupplied by said needle, said second bevel gear being rotated in adirection opposite to the hook whereby the hook takes the thread loopsupplied by said needle.